Backpedaling from what you just said makes you seem like a coward.
Going back on what you said like that is very cowardly.
Backpedaling from what you just said ( 適当に今こそ立場を変えようとすること)makes you seem like a coward. ( それこそが卑怯者だよ)
Going back on what you said like that( 今立場を変えて 前と逆のことを言うなんて) is very cowardly. ( とても情けないですよ)
Telling us something like that now just sounds like a lame excuse.
この場合、次のような言い方ができますよ。
ーTelling us something like that now just sounds like a lame excuse.
「今更そんなこと言っても、苦しい言い訳にしか聞こえないよ」
a lame excuse で「苦しい言い訳」と言えます。
ご参考まで!